1. Field of the Invention
The present invention relates to a resin sealing type semiconductor device wherein a very small semiconductor chip is sealed in a package with resin.
2. Description of the Related Art
Semiconductor chips have been reduced in size in accordance with miniaturization of elements. Generally, as the size of a semiconductor chip decreases, the mechanical stress thereof lowers, and, thus the semiconductor chip is more difficult to break. The small semiconductor chip has a more reliable temperature a variation than a large one and it can be manufactured at low cost. Using small semiconductor chips, a semiconductor device whose operating speed is high, power consumption is low, and electrical characteristic are good, can be achieved.
FIG. 1 is a cross sectional view showing a semiconductor device in which a very small semiconductor chip having the above-described features is sealed with resin. Semiconductor chip 12 is die-bonded onto bed 11 of a lead frame, lead 13 of the lead frame is connected to electrode pad 14 on chip 12 by bonding wire 15 and they are sealed in with mold resin 16. Since the lead frame to be processed is limited in size, lead 13 cannot be arranged sufficiently close to semiconductor chip 12 and inevitably bonding wire 15 is lengthened.
Although bonding wire 15 is in a correct position before the semiconductor chip is sealed with resin, it is deformed by the pressure exerted during the resin sealing as indicated by broken line A in FIG. 1, and is brought into contact with another bonding wire. There is a strong possibility that bonding wire 15 becomes defective.
One method for solving the above problem, is to connect chip 12 and lead 13 by TAB (Tape Automated Bonding) tape 21 using a TAB technique, as shown in FIG. 2. The TAB technique is as follows. TAB tape 21 is formed by sticking electrode pad 14 and a thin-film wire made of Cu or the like corresponding to lead 13 on a resin film. The TAB tape allows electrode pad 14 and lead 13 to be bonded together.
TAB tape 21 resists the pressure exerted when the chip is sealed with resin and thus does not deform. Since electrode pad 14 and lead 13 can be bonded, the productivity of semiconductor devices is high. According to the TAB technique, however, a bump (projected electrode) 22 needs to be formed on electrode pad 14 so that the electrode pad does not contact the edge of the chip, and the chip is not damaged by the bonding operation, and a special device for forming the bump is required. For this reason, an equipment investment in manufacturing process increases the manufacturing cost and it is economically difficult to apply the TAB technique to the semiconductor device of the present invention whose price is low.